Figure 4.
Rapid development of arteriovenous malformations (AVMs) in association with pubic symphysis following endothelial cell–specific ENG (endoglin) deletion in adult mice. A, Ventral vessels of the pubic symphysis in control (left) and Eng-iKOe (right) mice, following systemic perfusion with latex (blue). Scale bar=1 mm. B, Area occupied by latex perfused vessels as a proportion of the total pubic symphysis area (marked by dotted lines) is significantly greater in Eng-iKOe mice compared with controls. Data were analyzed by Student unpaired t test (n=5/group). C, Pubic symphysis of control or Eng-iKOe mice, stained for CD31 (cluster of differentiation 31) or YFP (yellow fluorescent protein) to visualize the vasculature. Upper panels (scale bar=1 mm). Bottom panels (scale bar=200 μm) correspond to boxed areas of upper panels (scale bar=1 mm). D, Quantification of vessel diameters (vessel area/vessel length, averaged across individual vessels, excluding capillaries with a diameter <8 μm) of control (n=7) and Eng-iKOe (n=6) mice reveals increased vessel size following ENG deletion. Data analyzed by Mann-Whitney U test. E, Trend toward reduced number of branch points following ENG deletion (n=4–6 mice). Data were analyzed by Student unpaired t test with Welch correction. F, Staining for αSMA (alpha smooth muscle actin; white) and CD31 (cluster of differentiation 31; magenta) reveals extensive coverage of AVMs by αSMA-positive cells. Scale bar=50 µm. G, No difference in circulating VEGF (vascular endothelial growth factor) protein was observed between control and Eng-iKOe mice 5 wk after ENG depletion. Data were analyzed by Mann-Whitney U test (n=11–13/group). H, Expression of Vegfa transcripts assessed by quantitative polymerase chain reaction is significantly higher in pubic symphysis cartilage compared with other tissues in normal control mice (n=3–5/group). Data were analyzed by 1-way ANOVA with Bonferroni correction.